The technically correct answer is: because no one has written impl Add<f64> for i32 {}. The cheeky answer is: because Rust doesn’t want you to shoot yourself in the foot. The longer, potentially more useful answer is… In computers, integers and floating point numbers both have a limited range, ultimately driven by the number of … Read more
The reason the quotients in your test case are not equal is that in the math.floor(a/b) case, the result is calculated with floating point arithmetic (IEEE-754 64-bit), which means there is a maximum precision. The quotient you have there is larger than the 253 limit above which floating point is no longer accurate up to … Read more
Here is a version with all optional type annotations and error handling which may be useful for beginners like me: use std::io; fn main() { let mut input_text = String::new(); io::stdin() .read_line(&mut input_text) .expect(“failed to read from stdin”); let trimmed = input_text.trim(); match trimmed.parse::<u32>() { Ok(i) => println!(“your integer input: {}”, i), Err(..) => println!(“this … Read more
new Integer(123) will create a new Object instance for each call. According to the javadoc, Integer.valueOf(123) has the difference it caches Objects… so you may (or may not) end up with the same Object if you call it more than once. For instance, the following code: public static void main(String[] args) { Integer a = … Read more
There’s no constant for this, but I think it’s more reasonable to hard-code the number in Postgres than it is in Java. In Java, the philosophical goal is for Integer to be an abstract value, so it makes sense that you’d want to behave as if you don’t know what the max value is. In … Read more
Split on commas, then map to integers: map(int, example_string.split(‘,’)) Or use a list comprehension: [int(s) for s in example_string.split(‘,’)] The latter works better if you want a list result, or you can wrap the map() call in list(). This works because int() tolerates whitespace: >>> example_string = ‘0, 0, 0, 11, 0, 0, 0, 0, … Read more
They are completely equivalent when used with printf(). Personally, I prefer %d. It’s used more often (should I say “it’s the idiomatic conversion specifier for int“?). (One difference between %i and %d is that when used with scanf(), then %d always expects a decimal integer, whereas %i recognizes the 0 and 0x prefixes as octal … Read more
Well, the API for Integer.valueOf(String) does indeed say that the String is interpreted exactly as if it were given to Integer.parseInt(String). However, valueOf(String) returns a new Integer() object whereas parseInt(String) returns a primitive int. If you want to enjoy the potential caching benefits of Integer.valueOf(int), you could also use this eyesore: Integer k = Integer.valueOf(Integer.parseInt(“123”)) … Read more
I assume you want to read an entire line, and parse that as input. So, first grab the line: std::string input; std::getline(std::cin, input); Now put that in a stringstream: std::stringstream stream(input); and parse while(1) { int n; stream >> n; if(!stream) break; std::cout << “Found integer: ” << n << “\n”; } Remember to include … Read more